Fluid Conduit with Self-Healing Protective Sleeve

ABSTRACT

A fluid conduit having a self-healing sleeve in a spaced relationship from the conduit to provide protection against leaks due to ballistic projectiles, such as small arms fire.

TECHNICAL FIELD

The present invention relates in general to the field of aircraft fuelsystems, in particular, aircraft fuel conduits. The present inventioncould also be applied to protect aircraft lube oil and hydraulicconduits.

DESCRIPTION OF THE PRIOR ART

Self-healing materials have been around for many years. There arevarious uses for self-healing materials such as naturalrubber/polyurethane and nitrile rubber. The main problem with theseself-healing materials is that it can take several seconds, evenminutes, for these materials to seal after being penetrated. Because ofthese shortcomings, it has not been advantageous to use theseself-healing materials as protective sleeves for aircraft fluid conduitsto protect the fluid conduits from leaking in the event the fluidconduits are penetrated by a ballistic projectile.

However, some self-healing materials, such as a self-healing ionomerknown as Surlyn® 8940 (available from DuPont Packaging and IndustrialPolymers, Wilmington, Del.), seal instantaneously.

Some have attempted to create self-healing laminated conduits, but suchconduits are relatively expensive and heavy, and suffer from the slowhealing times associated with their components. Additionally, because ofthe integrated nature of the laminated conduit, pressurized fluidswithin the laminated conduits exert instantaneous pressure on theprojectile opening interfering with the self-healing process.

While the self-healing systems described above represent significantdevelopments, considerable shortcomings remain.

SUMMARY OF THE INVENTION

There is a need for a fluid conduit having a self-healing protectivesleeve that heals instantaneously.

Therefore, it is an object of the present invention to provide a fluidconduit having a self-healing protective sleeve that healsinstantaneously.

It is another object of this invention to provide a self-healingprotective sleeve that may be retrofitted into existing conduit systems.

A further object of this invention is to provide a method for preventingfluid leaks due to projectile impacts on fluid conduits.

These objects are achieved by providing a self-healing protective sleevethat heals instantaneously, a fluid conduit incorporating the protectivesleeve, and a method for preventing fluid leaks due to projectiles.

The present invention provides significant advantages, including: (1)the sleeve prevents leakage of vital fluids in the event of a ballisticstrike to a fluid conduit; (2) the sleeve can be installed over aconventional fluid conduit; (3) ballistic penetrations can be closed inmicroseconds; (4) the device may be installed over existing fluidconduits; and (5) aircraft survivability is increased, particularly inthe event of small arms ballistic fire.

Further objects and advantages of this invention will become apparentfrom a consideration of the drawings and ensuing description.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, includingits features and advantages, reference is now made to the detaileddescription of the invention taken in conjunction with the accompanyingdrawings in which like numerals identify like parts, and in which:

FIG. 1 is a schematic of a fluid conduit having a self-healingprotective sleeve according to the preferred embodiment of the presentinvention;

FIG. 2 is a sectional view of the self-healing protective sleeve of FIG.1;

FIG. 3 is a sectional view of the seal on one end of the self-healingprotective sleeve of FIG. 1;

FIG. 4 is a perspective view of a fluid conduit having a self-healingprotective sleeve according to the present invention installed in a testchamber prior to penetration by a ballistic projectile; and

FIG. 5 is a perspective view of a fluid conduit having a self-healingprotective sleeve according to the present invention installed in a testchamber after penetration by a ballistic projectile.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Self-healing protective fuel conduit sleeves are primarily intended formilitary applications, because they address improved survivability inthe face of small arms ballistic fire. This technology may be applied toany fixed or rotary wing aircraft where fuel leakage, especially afterballistic impact, and fire is a concern.

Referring now to FIG. 1 a sleeve 10 comprised of a self-healing materialis installed over a length of conduit 15. Conduit 15 may be standardmetal or rubber/nitrile fuel conduit 15, in which case sleeve 10 isproposed for the purpose of containing a fuel leak or preventing a fireafter ballistic penetration of the fuel conduit 15 inside of the sleeve10.

Continuing with FIG. 1, between sleeve 10 and conduit 15 is space 20.Space 20 is created by the difference in size between sleeve 10 andconduit 15 and maintained by seals 25. Seals 25 provide a fluid sealbetween conduit 15 and sleeve 10 to contain any fluid that may leak fromconduit 15 while also positioning sleeve 10 in a spaced relationshipfrom conduit 15 to create space 20. Also shown in FIG. 1 is fluid 30within conduit 15.

FIG. 2 is a cross sectional view of the conduit 15 and sleeve 10 of FIG.1 showing again the fluid 30 within conduit 15 and space 20 betweenconduit 15 and sleeve 10. While conduit 15 and sleeve 10 are shownhaving a circular cross section, the invention is not limited to suchcross sections. Conduits 15 of any cross section may be enhanced bysleeves 10 of any cross section so long as a space 20 is maintained.

FIG. 3 is a sectional view of one embodiment of the seal 25 shown inFIG. 1. A spacer 35 is sized to fit over conduit 15 in a sealing fashionand within sleeve 15 in a sealing fashion. The cross section of spacer35 is determined by the shapes of both sleeve 10 and conduit 15. Seal 25may then be secured by a compression strap 40 as shown in FIG. 3 tosecure the positioning of spacer 35. This embodiment of seal 25 is shownfor exemplary purposes only and it is readily apparent that othersealing means may be used to achieve the invention. For example, sleeve10 may be tapered into direct sealing engagement with conduit 15. Ofimportance is that space 20 be maintained and sealed such that fluid 30that may leak into space 20 is contained within space 20.

FIG. 4 is a perspective view of a fluid conduit 15 having a self-healingprotective sleeve 10 according to the present invention installed in atest chamber prior to penetration by a ballistic projectile. In thisview, conduit 15 is black while sleeve 10 is transparent, therebyhighlighting space 20 between conduit 15 and sleeve 10.

FIG. 5 is a perspective view of a fluid conduit 15 having a self-healingprotective sleeve 10 according to the present invention installed in atest chamber after penetration by a ballistic projectile. In this view,fluid 30 is shown partially filling space 20. Fluid 30 has leaked fromconduit 15 due to penetration 45 in conduit 15 by a projectile (notshown) but has been contained within space 20 by self-healing sleeve 10and seals 25.

The proper functioning of sleeve 10 depends on the material selected tocreate sleeve 10. The self-healing ionomer known commercially as Surlyn®8940 is particularly well suited for use in sleeve 10. Other similarself-healing materials may also be adaptable to the invention. As shownin FIG. 5, sleeve 10 is self-healing, such that when penetrated with asmall projectile the penetration 45 automatically closes nearlyinstantaneously. By spacing sleeve 10 apart from conduit 15 sleeve 10 isallowed to self-heal prior to fluid 30 being forced into penetration 45.

A method for preventing fluid 30 leaks due to projectiles comprises thesteps of: identifying a length of fluid conduit 15 that may be exposedto projectiles; selecting a self-healing sleeve 10 that is sized to beplaced over the conduit 15 in a spaced relationship; placing theself-healing sleeve 10 over the conduit 15; securing the sleeve 10 in aspaced relationship with the conduit 15 to create a space 20 between theconduit 15 and the sleeve 10; and sealing the space 20 between theconduit and the sleeve. The method may be further streamlined bycompleting the securing and spacing in a single step of installing seals25 that maintain both the spaced relationship and the sealing of thespace 20.

The self-healing ionomer used in the present invention self-heals nearlyinstantaneously, as opposed to conventional self-healing materials thatcan take several seconds or minutes to seal after perforation. Aself-healing protective sleeve 10 works by rapidly (microseconds)closing the ballistic penetration 45 in the sleeve to prevent fuel orother fluids 30 from escaping from the ballistically penetrated sleeve10 over conduit 15, so as to reduce fluid 30 leak from the conduit15/sleeve 10 system and to reduce the resulting threat of fire.

The present invention reduces the probability of an aircraft fuel systemfire by containing the fuel after penetration of a fuel conduit, and byseparating fuel escaping from the fuel source, e.g., conduit, fromignition sources outside the confines of sleeve 10. Installed as asleeve enveloping a fuel conduit, the sleeve of the present inventioncan significantly reduce the quantity of fuel escaping into a dry bay,or area surrounding a fuel source, thereby reducing the risk of asustained fire.

The invention is unique because, unlike conventional self-healing fuelconduits, the present invention uses an instantaneously self-healingionomer, preferably a Surlyn® ionomer, which self-heals instantaneouslyas opposed to requiring several seconds or minutes to seal. The presentinvention is also unique because it is designed to be rapidly installedover existing fuel conduits, as opposed to replacing existing fuelconduits. The combination of the advanced material, e.g., self-healingionomers or other rapidly self-healing materials, and fuel conduitprotection as a sleeve, is considered unique.

While this invention has been described with reference to anillustrative embodiment, this description is not intended to beconstrued in a limiting sense. Various modifications and otherembodiments of the invention will be apparent to persons skilled in theart upon reference to the description.

1. A protective conduit sleeve, comprising: a length of self-healingmaterial sized to be positioned in a spaced relationship over a conduit.2. The sleeve according to claim 1, further comprising: at least oneseal between the self-healing material and the conduit.
 3. The sleeveaccording to claim 1, wherein the self-healing material is Surlyn®. 4.The sleeve according to claim 1, wherein the self-healing material isSurlyn®
 8940. 5. A fluid conduit system, comprising: a conduit for fluidmaterials, the conduit having a cross section; and a self-healing sleevesized to create a space between the conduit and the sleeve when thesleeve is placed over the conduit.
 6. The fluid conduit system accordingto claim 5, further comprising: a seal sized to maintain the spacebetween the sleeve and the conduit.
 7. The fluid conduit systemaccording to claim 6, wherein the seal further creates a fluid sealbetween the conduit and the sleeve.
 8. The fluid conduit systemaccording to claim 5, wherein the sleeve is comprised of Surlyn®.
 9. Thefluid conduit system according to claim 5, wherein the sleeve iscomprised of Surlyn®
 8940. 10. A method of preventing fluid leaks due toprojectiles, the method comprising the steps of: identifying a length offluid conduit that may be exposed to projectiles; selecting aself-healing sleeve that is sized to be placed over the conduit in aspaced relationship; placing the self-healing sleeve over the conduit;securing the sleeve in a spaced relationship with the conduit to createa space between the conduit and the sleeve; and sealing the spacebetween the conduit and the sleeve.
 11. The method according to claim10, wherein the securing and spacing are completed in a single step ofinstalling seals that maintain both the spaced relationship and thesealing of the space.